Mekata Hirohisa, Minamino Tomoya, Mikurino Yoko, Yamamoto Mari, Yoshida Ayako, Nonaka Nariaki, Horii Yoichiro
Organization for Promotion of Tenure Track, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 8892192, Japan; Center for Animal Disease Control, University of Miyazaki, 1-1 Gakuen-Kibanadai-Nishi, Miyazaki 8892192, Japan.
Divisions of Research & Education for Livestock and Veterinary Clinic, Honkawa Ranch, Takase, Hita 8770056, Japan.
Vet Parasitol. 2018 Nov 15;263:1-4. doi: 10.1016/j.vetpar.2018.09.017. Epub 2018 Oct 1.
Bovine theileriosis, caused by Theileria orientalis, is endemic from East Asia to Oceania. Even though the disease is mainly transmitted by Haemaphysalis ticks, the T. orientalis parasite can also be transmitted vertically. To develop proper control measures, the frequency of each transmission route must be elucidated. However, the frequency of vertical transmission, including transplacental transmission, of T. orientalis in naturally infected cattle is still controversial. This study aimed to clarify the frequency of the vertical transmission of T. orientalis in naturally infected cattle. Blood samples were collected from 204 T. orientalis-infected dams and their 211 newborn calves (including 7 sets of twins) within the first 24 h as well as 30 days after birth. Furthermore, 31 and 24 calves born to T. orientalis-infected and uninfected dams, respectively, were continuously surveyed for infection until 5 months of age. A total of 5 (2.4%) dams were diagnosed with mild anemia, whereas most of the dams were asymptomatic based on hematological examination and clinical signs. PCR analysis was performed on whole blood to determine the presence of T. orientalis in calves, and no calves were PCR positive 0 and 30 days after birth. However, 9.6% and 0% of the calves born to T. orientalis-infected and uninfected dams, respectively, tested positive at 3 and 5 months of age. The sampled calves were fed in-house, and the survey was conducted during the cold season; thus, horizontal transmission through blood-sucking insects rarely occurred. Therefore, the vertical transmission of T. orientalis took as long as 3 months to become detectable by PCR and occurred in approximately 10% of field cattle.
由东方泰勒虫引起的牛泰勒虫病在东亚至大洋洲地区呈地方性流行。尽管该病主要通过血蜱传播，但东方泰勒虫寄生虫也可垂直传播。为制定适当的防控措施，必须阐明每种传播途径的发生频率。然而，东方泰勒虫在自然感染牛中的垂直传播频率，包括经胎盘传播，仍存在争议。本研究旨在阐明东方泰勒虫在自然感染牛中的垂直传播频率。在出生后的头24小时内以及出生后30天，从204头感染东方泰勒虫的母牛及其211头新生犊牛（包括7对双胞胎）采集血样。此外，分别对31头和24头由感染和未感染东方泰勒虫的母牛所生的犊牛进行持续监测，直至5月龄。共有5头（2.4%）母牛被诊断为轻度贫血，而根据血液学检查和临床症状，大多数母牛无症状。对全血进行PCR分析以确定犊牛中是否存在东方泰勒虫，出生后0天和30天没有犊牛PCR呈阳性。然而，分别由感染和未感染东方泰勒虫的母牛所生的犊牛中，9.6%和0%在3月龄和5月龄时检测呈阳性。所采样的犊牛在室内饲养，且调查在寒冷季节进行；因此，通过吸血昆虫的水平传播很少发生。因此，东方泰勒虫的垂直传播需要长达3个月才能通过PCR检测到，并且在大约10%的田间牛中发生。
